Electric heater



May 5, A1925.

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May 5, 1925. 1,537,035

C'. L. HESLER ELECTRIC HEATER Filed- Sept. 18, 1925 2 Sheets-Sheet 2 00F eaVyWeWS/VVMM/VV A A A A A A A AAed/-Um I Jenifer: 60 Charfs LA. HeisIeI-s Patented AMay 5, 1925.

UNITED STATES PATENT oFllcE.

CHARLES L. HEISLER, F SCHVENECTADY, NEW YORK, ASSIGNOR T0 'GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATER.

. Application filed September 18, 1923. Serial No. 663,481.

To all 'whom t may concern:

` Be it known that I,v CHARLES L, HErsLER,

a citizen of the United States, residing at Schenectady, in the county of Schenectady', State of New York, haveV invented certain new` and useful Improvements in Electric Heaters, of which the following is a speci# cation. My invention relates to electric heaters, more specifically. to electric heaters provided with temperature responsive means for controlling the heating'circuit, and has for its object the provision of simple, reliable `and eflicient temperature responsive l5 control Ymeans which may be given different temperature settings. f

While m invention has application to electrically lieated devices in general, ithas particular application to electrically heated flat-irons.

In the construction ofitemperature re-,.

particularly where the parts are punched' or otherwise cheaply formed. Furthermore, in flat-irons for general use it is desirable to have the temperature responsive control device adjustable to maintain differ,- ent ironing temperatures. A low tempera- Jture is desirable for light fabrics, a slightly higher temperature for medium work, and a still higher temperature for heavy goods. In carrying out my invention, I arrange' the various parts so that all lost motion is taken up by a single spring which has the function also of causing quick opening and closingof the control switch for the heating circuit. I have also provided an adjustment whereby the temperature control means may be set to maintain the desired temperature. My invention also comprehends a safety device which is maintained inoperative while the iron is in use but which operates when the iron is not in use to lock the control switch in open position after it has been opened by the thermostat, it being impossible, however, to prevent the opening of the 5o switch under the control of the thermostat.

For a more complete understanding of :my invention reference should be had Ato the accompanying drawings in which. Fig.. l

is a section elevation view of a fiat-iron provided with temperature control means embodying my invention; Fg. 2 is a lan view-with thecover removed of the iiatdron shown in Fig. 1; Fig. 3 is an enlarged viewA plicable to the control of various other electrically heated devices. This flat-iron comprises an ironing base 10, which is to be heated, provided with a central .cavity 11 in which the temperature control means is mounted, and with a groove 12 extending adjacent its edge in which .is clamped a horse-shoe shaped heating element 13 having its terminals 14 and 14a exposed at the rearward end of the flat-iron base l0. The particular heating unit shown is of the sheath wire type consisting of a metallic sheath 15 in which is a helical resistance conductor 16 embedded in compacted insulating material 17. Preferably the groove 12 is substantially V-shaped, the heating.

unit having a. corresponding shape whereby maximum contact with the sides of the groove is obtained to permit the free conduction of.heat therefrom to the body 10. The heating unit is forced into the groove by means of screws 18, 19 and 2O cooperating with a clamping member 21 placed on the heating unit.

To provide for automatic temperature control of the heating unit 13, a thermostat 22 is used. This thermostat comprises a plurality of metallic strips or bars having alternately high and low coefficients of expansion, as shown 'in Fig. 4. Bars 23 hav- I .ing high-'coeflicients of expansion are made of any suitable material, such as brass, while the bars 24 having low coetlicients of expansion are made of a suitable material, such as invar metal. To provide -for the necessary tensile strength the bars 23'are made much heavier than the bars 24 due to the much greater strength of the invar metal. The bars 23 are each provided with a. longitudinal groove 25 on their upper and lower' sides in which the bars 24 fit. This construction v,encloses the bars 24 protecting them from oxidation and also exposes the barsv 23 so that heat is rapidly conducted to them from the flat-iron body, whereby the bars 23 are made quickly responsive to changes in temperature. In the particular thermostat shown in Fig. l, seven invar bars 'by providing ltwo pairs of projections` 26',

27 and 26a, 27n on the respective ends of the bars 24. These projectionsextend laterally outward from the sides oi the bars 24 for a slight distance and then pairs 2G and 27 are turned upward and pairs 26a and 27L downward so as Vto cooperate with notches 28, 2 9 and v28, 29a foi-ined in corresponding positions in the respective ends of bars 23. As shown in Fig. 4, the inner projections of the bars 24 fit in the notches 28, 29 and 28a, 29a respectively while the outer projections of bars 24 fit outside the ends of the bars 23. The construction of the upper and lower bars 23 is slightly different from the intermediate ones. The upper bar 232L has the longitudinal groove 25 only on its lower side and at its left hand or fixed end is pro-l vided with an additional pair of notches 30 andf31. The lower bar 23b` has the slot 25 only on its upper face and has its free end forming the operating end of the thermostat extending a short distance beyond the other bars and provided with a knife-edge bearing 32. This particular method of securing the barsttogether provides for cheapness of construction and ease of assembly.

The assembled thermostat 22 is enclosed in a casing consisting of a U-shaped clamping member 33 (Fig. A5) which is secured t04 an upper supporting plate 34. The member 33 is substantially equal in length to the length of the thermostat so that the end of the lower bar 23b projects some-what, as shown in Fig. 1. By means of the casing the bars are held in their assembled relation,

the casing being suliiciently loose, however, to permit the bars to slide freely therein and with respect to each other.

The'u'pper bars 23a has'its left-hand end ironing base and is clamped therein in good heat conducting relation with-.the base by screws 18,19, 20.' Spring washers 37 are .l in length.

member 21 to assure the seating of theheating unit in place whenv the thermostat is` seated.

In the operation ot the thermostat, upon an increase.. of temperature, for'example, eachof the bars 23 willexpand and increase l Beginning with the top of bar 23, it will be observed that the expansion of each bar will be transmitted together with the expansion of the previous bars to the next succeeding bar by .means of the connecting bars 24. The movement applied to; the end of the thermostat is thus equal to the summation of the expansions of each otthe bars 23 less lthe summation 'ot the expansionsof the bars 24. The bars 24 have very nearly a zero expansion coeiicient, however, so thaty thefmovement applied to the end of the thermostatis substantially equal to the expansion of a rod havingv a length equalyto the sum of the lengths ofybars 23. This construction has the advantage of utilizng the relatively great operating force of a bar thermostat in a comparatively short space.

lReferring t'o Fig. l, the knife-edge bearing end 32 of the thermostat cooperates with adown-turned trigger-shaped member 40 having an intermediate fixed fulcrum 41 carried by member 33 and secured. at its upper end to a skeleton arm '42.comprising parallel side bars 42@L and 42". The

si i

trigger member 40 and arm 42 taken together constitute an operating member having a fixed fulcruin 41. On the right hand end of arm 42 is a bearing rod 43 which is pressed toward the left by a spiral spring 44. lThe pointed bearing end of rod 43 is seatedin a depression in an upright lever 45 having a fixed fulerum 45a at its upper end and cooperating at its lower end with the end of a member 46 which extends upwardly for a short distance to a point between the sides of arm 42 and thenextends at right angles to the left to a point adjacent .the left end of arm 42 where mem ber 46 is vprovided with a knife-edge end. Cooperating with the left-hand end of arm 42 knife blade member 47 which cooper` ates in turn with one side of a tilting block 48 carrying a skeleton switch arm 49, the

opposite side of block 48 resting against the knife-edge end of member 46. As shown in Fig. 3, the knife-blade member 47 is provided at its end with lateral projections 47a and 47" between which the tilting` block 48 rocks and also with a central projection 47c which tits between the two sides of arm 42. By means of this construction the member 47 is held in position onk arm 42 and the tilting block 48 held in its proper position on the member 47.

rI he member 46 is supported at its lefthand end in a predetermined position by means of a member 50 secured thereto and extending upwardly into screw-threaded engagement with a knob 51 which is rotatably mounted on a support 52`straddling the control mechanism and mounted on the supporting plate 34. By turning knob 51.

provided as an extension of support 52 onwhich are mounted insulated stationary contacts 54 and 55 (Fig. 3) in position to. cooperate with bridging contacts 56 and 57 carried by the4 switch arm 49. The contacts 56 and 57 are 'insulatedffrom the switch'arm but electrically connected to each other. Mounted'on support 53 are also terminal pins 58 and 59 (Fig. 2) adapted for a plug connector, pin 58; being connected directly to -terminal 14 of the heating unit; while pin 59 is connected through the switch contacts to terminal 14. The fixed pivot` a also is carried by support 53.

As Shown in Fig. 1 of the drawing, the switch arm 49 is in open circuit position caused by lateral movement of the end-of the thermostat toward the right due to the occurrence of the predetermined maximum temperature for which the device was set.

l After the heating circuit has thus been opened the flat-iron will cool ofi' whereby the brass bars 23 of the thermostat will con- .tract causing the free end of the thermostat to move back toward the lett. As this movement of the thermostat takes place it will be observed that the .left-hand end of the arm 42 will'be moved upward slightly, the arml rocking about the fixed fulcrum 41. As this upward movement of arm' 42 takes place it will be'observed that knife blademember v47 will be tilted about its pivot point on the tilting block 48 to a position of alignment with the direction of the force applied by spring 44. and then nioved slightly beyond this position upon thefoc-A currence of a predetermined minimum temperature, when spring 44 will be in a direction to move the tilting block downward in a counterclockwise direction as viewed in 1 about its pivot on ythe -end of be snapped downward to open position as turned in one direction or t-he other.

shown in the drawing. The heating circuit is thus automatically opened and closed in response to the temperature of the fiatiron so as to maintain the temperature within a predetermined range determined by the minimum and maximum temperature limits Aat whichthe device operates.

In order to regulate the temperature which will be maintained, button 51 is For example, to increase the temperature, button 51 will be turned in such direction as to raise the left-hand end of member 46, this being effectedv through the screw confnection with the supporting member 50.

To lower the temperature, button 51 is turned in such direction as to lower the end lof member 46. By means of this adjust.-

` ment the fiat-iron can be set to maintain any one of the ftemperaturecycles indicated in Fig. 6. For light fabrics the control mechanism will be set to maintain a temperature rangeY substantially between-420 and 480 deg. F. as shown by the curve 60; for medium work the temperature range will be substantially between 46() and 540 deg. F. as indicated by curve 61; while for heavy work a temperature range of substantially between 520 and 580 deg. F. will be main tained as indicated by curve 62.

For the purpose of giving the switch arm 49 a more positive kick-off or movement from one position to the other, a screw pin 63 is secured to arm 42 near its outer end. This pin extends freely through an aperture 64 in member 46 and is provided with two spaced flanges 63a and 63b between which y the switch arm moves. It will be observed "that the pin extends through a slot in the switch arm sothat it is embraced by the two sides of the switch arm. Upon movement of arm 42 in an upward direction the lower flange 63h will engage the switch arm at the 'kick-cti point tending to positively start it upward, and upon movement of arm 42 downward the upper tiange 63 will positively start the rswitch arm downward. u

A cover 65 and a handle 66 are provided for the flat-iron. These parts are secured to'each other and to the iron'ng base 10 by means of an extension of screw 18 and a screw 67 connecting with support 34. A

plug guard and heel rest 68 is also provided. v

This member 68 also serves as an additional A,protecting means for the control mechamsm.

For the purposeof preventing the heating oi the iron when not 1n use in the event that it is inadvertently left connected to the gated opening 72 in the cover into the interior of the flat-iron where it engages with a horizontal lever arm 73 (Fig. 3) pivoted at 74v to the supporting plate 34. On the right-hand end of lever 73 is a laterally extending latching projection 73 'which extends above arm 42 without interfering with its movement and is arranged to slip over switch arm 49, as shown in Fig. l, when the arm is in its lowermost or open circuit position. The lever 70 is biased about its pivot by a spiral spring 75 so as to' tend to move the latching projection 73a inward over the vswitch arm. In the operat`on of 'this latching device, while the iron is in use. the Aoperator will unconsciously depress button (if) by the switch arm is released and thereupon with his thumb and thus maintain :latch 73"4 in the position shown in Fig. 3 such that it will not interfere with the circuit closing movement of the switch arm. In case, however, the iron is put aside without discounecting it from the heating circuit. then latch 73'V will be forced by spring 75 upon releasing thumb rest (i9 into engagement with theside ofthe switch arm and when the switch arm is moved downward by the theremostat to open the heating circuit upon the oecurrence of the predetermined 'maximum temperature, the latch will slip over the switch arm and secure it in ,open circuit position. As the iron cools down thereafter, it will thus be. impossible for the heating circuit to be again closed. Upon resuming work or upon lifting the iron preparatory to resuming work.- the operator will without conscious eforttlepress thumb rest 69 whereis moved upward closing the heating circuit. The inneriend of latch 73a-is made square so that 'it is impossible for it to slip under the switch arm or in any way Aoppose the movement of the 'switch arm downward to open circuit position under the control of the thermostat. When the thumb rest is released with the switch closed the inner squared end of the latch comes to rest against vthe side of the switch arm but vdoes not interfere with its downward movement to open position.

It will be observed that the various parts of the control mechanism are secured to their supports, fixed fulcrums 41 and 45a, and in their proper cooperating relation with each other and with the thermostat by means of the spring 44. The spring therefore takes up all lost motion so that the control device is immediately responsive to movement ofthe thermostat. `In fact, to take the control device apart, it is necessary only to release the spring 44 when the parts will be released. This construction makes it possible to` use stamped or otherwise cheaply formed parts and yfacilitates the assembly i 1 of the parts.

-While I have described my invention.y as

`members forming an opera-ting connection embodiedlin concreteform and as operating in a specific manner in accordance with the provisions 'of the patent statutes, it should be understood that I do'not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is: Y

l. Thermostatic controlmeans for electric heaters and the like, comprising a thermostat, circuitl control means, a plurality of members forming an operating connection lbetween said control means and said thermosta-t, and a common means for holding said members in their various cooperating relations and for moving said control means from one position to another4 upon movement of said thermostat.

2. Thermostatic control means for electric heaters and the like, comprising a thermostat, circuit control means, a plurality of between said control means and said thermostat, stationaryv isupports forming fulcrums for said members, and a spring for holding said members on said supports in their various cooperating relations and for moving said control means from one position to another upon movement of said ther` mostat.

'3. -Thermostatic control means for electric heaters and the like, comprising a thermostat, a control switch, a member having a fixed fulcrum and pivotally cooperating with said switch and said thermostat, a secondmember having a fixed lfulcrum and pivotally cooperating with said first member, a

' operating relations and to snap said switch from one position to another upon movement of said thermostat.

4. Thermostatic control means for electric heaters and the like comprising a thermostat, a tilting block, a switch arm carried by said tilting block,a member having a fixed fulcrm and pivotally cooperatmg with said tilting block and said thermostat, a second member having a fixed fulcrum and ivotally cooperating with said first memer, a third member pivotally cooperating with said second member and said vtilting block, and a spring carried by said vfirst member forming a part ofthe pivotal connection with said second member acting to hold said members on their fulcrums in their various cooperating relations and to snap said switch arm from one position to another of members forming an operating connection between said control means and said thermostat, a common means for holding said members in their various cooperating relations and for moving said control means from one position to another upon move.

ment of said thermostat to maintain a predetermined temperature, and means for adjusting one of said members to regulate said temperature. f

6. Thermostatic control means for electric heaters and the like, comprising a thermostat, an adjustable member, a switch arm pivoted on said adjustable member, and a Second member cooperating with said thermostat and yacting on said switch arm to move it about its pivot to open and close the heater circuit, and means for adjusting said adjustable memberto change the temperature setting.

7. Thermostatic control means for electric heaters and the like, comprising a thermostat, a member having a Xed fulcrum actua-ted by said thermostat, a second member having a fixed fulcrum and pivotally co- 'operatingwith 'sa-id rst member, a third member pivotally cooperating with said second member, a switch arm pivoted on said third member and .moved about its pivot by said first member upon movement of said thermostat to open and close the heater circuit, and means for adjusting said third member to change the temperature setting.

8. Thermostatic control means for electric heaters and the like, comprising a thermostat, a member having a fixed fulcrum actuated by said thermostat, a second member having a fixed fulcrum and pivotally cooperating with said rst member, a third member pivotally cooperating at one end with said second member, a tilting block pivoted on the other end of said third member and moved about its pvot by said rst member upon movement of said thermostat, a switch arm carried by said tilting block, and means for adjusting said third member to change le kposition of the pivot of said tilting 9. Thermostatic j control means for electric heaters comprising circuit control a substantially constant temperature, and

manually controlled means for holding the circuit open when it has been opened by said l tnermostatic means.

11. Thermostatic control means for electric fiat-irons and the like, comprising control means for the heatingcircuit thereof, thermostatic means associated with said control means so as to automatically open and close said circuit to maintain a substantially constant temperature,A and manually controlled means operative when the flat-iron is released for holding said control means in open circuit position after said control means has been openedby said thermostatic means.

12. Thermostatic control means for electric heaters, comprising circuit control means, a thermostat connected to operate said control means so as to open and close the circuit of the heater and maintain a substantially constant temperature and releasable latching means for holding said control means in open circuit position.

13. Thermostatic control means for electric fiat-irons and the like, comprising a control switch, a thermostat for opening and closing said switch, and means for latching said switch in open position, said latching` means being maintained inoperative while the iron is in use.

14. Thermostatic control means for electric flat-irons and the like, comprising a control switch, a thermostat for opening and closing said switch, .and manually controlled means for holding said switch open after it has been opened by said thermostat.

15. Thermostatic control means for electric Hat-irons and the like, comprising a control switch, a thermostat for opening and closing said switch, and manually controlled means operative while the iron is not in use to prevent closing of said switch, but maintained ineffective while the iron is in use whereby said switch is controlled by said thermostat 4to maintain a predetermined temperature.

16. Thermostatic control means for electric fiat-irons and the like, comprising a control switch, a thermostat Jfor opening and closing said switch, and latching means held inoperative without conscious eort of the operator while the iron is in use, but when released preventing reclosing of said switch after it has been opened by said thermostat.

17. Thermostatic control means for electric flat-irons and the like, comprising control means for the heating circuit thereof, l

pressed.

18. Thermostatic control means-for elec-I tric flat-irons and the like, comprising a thermostat, a control switch opened and closed by said thermostat, latching means biased to normally prevent closingof said switch, and a thumb rest operatively connected to said latching means whereby said latching nieans may be moved to allow said switch to close by depressing said thumb rest.

19. Therinostatic control means for electric flat-irons and the like, comprising a thermostat, a control switch opened and closed by said thermostat, latching means biased to normally prevent closing of said switch, and releasing means for said latchposition.

ing means actuated when the iron is in use to hold said latching means in inoperative 20. Thermostatic control means for electric iat-irons'and the like, comprising a thermostat, a control switch opened and closed by vsaid thermostat, latching means for holding said switch in closed position, a thumb rest pivotally-mounted on said iron, an operating connection between said thumb restl and said latching means, and a spring for biasing said thumb rest' to move said latching means in position to lock said switch after it has been openedby saidtherinostat.

In witness whereof, I have hereunto set my hand this 17th day of September, 1923.

CHARLES L. HEISLER. 

